This invention relates to an internal combustion engine of the type provided with an auxiliary combustion chamber in addition to a main combustion chamber, and more particularly to a gasoline injection internal combustion engine of the above type for automotive vehicles which can operate with an improved rate of fuel consumption, while, at the same time, attaining the purification of exhaust gases.
In an internal combustion engine of the type provided with an auxiliary combustion chamber in addition to a main combustion chamber, fuel is injected directly into the auxiliary combustion chamber to form a rich fuel-air mixture in the auxiliary combustion chamber, and a portion of the fuel passing from the auxiliary combustion chamber into the main combustion chamber is utilized to form a lean fuel-air mixture in the main combustion chamber so as to attain the so-called stratified charge combustion in which the fuel is subjected to primary and secondary combustion. While this stratified charge combustion is advantageous in reducing the amount of nitrogen oxides (NOx) among harmful components of engine exhaust gases, it has also the disadvantage of increasing the amounts of unburnt hydrocarbons (HC) and carbon monoxide (CO) due to the fact that the rich fuel-air mixture is formed and ignited in the auxiliary combustion chamber.
An internal combustion engine is known in which the combustion space is divided into a main combustion chamber and an auxiliary combustion chamber, and an intake valve and an exhaust valve are disposed in the main combustion chamber. In this engine, the main combustion chamber is connected to the auxiliary combustion chamber by a communication passage, and an ignition plug and a fuel injection nozzle are provided for the auxiliary combustion chamber, and a rich fuel-air mixture is produced in the auxiliary combustion chamber and initially ignited, and then the flame thus produced is utilized for causing secondary combustion of the fuel-air mixture in the main combustion chamber. In such an engine, air must be supplied from the main combustion chamber into the auxiliary combustion chamber without being extremely restricted by the communication passage, and the flame produced in the auxiliary combustion chamber must quickly spread throughout the main combustion chamber so as to ensure effective secondary combustion of the fuel-air mixture in the main combustion chamber.